Redetermination of MoPt3Si4 from single-crystal data

Knittel, S.; Francois, M.; Steinmetz, J.; Vilasi, M.

doi:10.1107/S1600536810054425

inorganic compounds

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Volume 67| Part 2| February 2011| Page i20

doi:10.1107/S1600536810054425

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Redetermination of MoPt₃Si₄ from single-crystal data

Stephane Knittel,^a Michel Francois,^a Jean Steinmetz ^a and Michel Vilasi ^a ^*

^aInstitut Jean Lamour, UMR 7198, Département 2, Université Henri Poincaré, Nancy Université, Faculté des Sciences et Techniques, BP 239, 54506 Vandoeuvre les Nancy CEDEX, France
^*Correspondence e-mail: michel.francois@lcsm.uhp-nancy.fr

(Received 5 November 2010; accepted 27 December 2010; online 22 January 2011)

The crystal structure of molybdenum triplatinum tetrasilicide, MoPt₃Si₄, determined previously from powder diffraction data [Joubert et al. (2010 ). J. Solid State Chem. 183, 173–179], has been redetermined using a single crystal synthesized from the elements by high-frequency melting. The redetermination provides more precise geometrical data and also anisotropic displacement parameters. The crystal structure can be considered to be derived from the PtSi structure type with an ordered substitution of Pt by Mo atoms, but leading to a very distorted Si network compared to the parent structure. Mo and Pt exhibit different coordination polyhedra. These are based on bicapped-square antiprisms, but with two additional vertices in cis positions for Mo, whereas they are in trans positions for Pt (as in PtSi). The coordination polyhedra for three of the Si atoms can be considered as highly deformed square antiprisms (as in PtSi), while the fourth Si atom has a bicapped trigonal–prismatic coordination geometry.

Related literature

For general background to molybdenum silicides, see: Littner (2003 ); Benarchid et al. (2009 ); Bernard et al. (2010 ); Cabouro et al. (2007 , 2008 ); Fitzer (1955 ); Knittel et al. (2010 ). For the structure determination of the title compound from standard X-ray powder diffraction data, see: Joubert et al. (2010). For the PAP correction program, see: Pouchou & Pichoir (1984 ).

Experimental

Crystal data

MoPt₃Si₄
M_r = 793.57
Orthorhombic, P n m a
a = 5.5121 (2) Å
b = 3.4951 (1) Å
c = 24.3078 (7) Å
V = 468.30 (3) Å³
Z = 4
Mo Kα radiation
μ = 92.80 mm⁻¹
T = 297 K
0.12 × 0.03 × 0.03 mm

Data collection

Bruker APEXII QUAZAR CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ) T_min = 0.031, T_max = 0.174
9779 measured reflections
1060 independent reflections
955 reflections with I > 2σ(I)
R_int = 0.040

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.067
S = 1.41
1060 reflections
50 parameters
Δρ_max = 2.16 e Å⁻³
Δρ_min = −3.81 e Å⁻³

Table 1
Selected bond lengths (Å)

Pt1—Si3ⁱ	2.406 (3)
Pt1—Pt1ⁱⁱ	2.9119 (6)
Pt2—Si1ⁱⁱⁱ	2.387 (3)
Pt2—Mo1^iv	2.9331 (10)
Pt3—Si3	2.405 (2)
Pt3—Pt2	2.8874 (5)
Mo1—Si4	2.535 (2)
Mo1—Pt2ⁱⁱⁱ	2.9331 (10)
Si1—Pt2^iv	2.387 (3)
Si1—Si2	2.711 (3)
Si2—Pt3	2.466 (3)
Si2—Si1	2.711 (3)
Si3—Pt1^v	2.590 (2)
Si3—Si3^vi	2.807 (5)
Si4—Pt2^v	2.407 (2)
Si4—Si4^vii	3.012 (5)
Symmetry codes: (i) -x+1, -y, -z+1; (ii) -x+1, -y+1, -z+1; (iii) x-1, y, z; (iv) x+1, y, z; (v) x, y-1, z; (vi) -x, -y, -z+1; (vii) $[x-{\script{1\over 2}}, y, -z+{\script{3\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999 ) and ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810054425/fi2101sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810054425/fi2101Isup2.hkl

checkCIF report

Comment top

Interest for studying the Mo—MP—Si (MP = Pt, Ru) system follows from the attractive properties of MoSi₂ regarding high-temperature oxidation. But early in the past, the first studies performed by Fitzer (1955) mentioned the poor behaviour of this material under oxidizing atmosphere at moderate temperatures (300–600°C) due to a catastrophic degradation, the so-called "pest phenomenon". Consequently, one of the challenges for application of MoSi₂ is to control the pest oxidation by adding alloying elements (Ru, Pt, B, Al, Ge, Y, Ti, Zr, Ta) (Littner, 2003, Benarchid et al. 2009) and/or by controlling the microstructure. Recently, the optimization of the microstructure led to fully densified materials showing dramatically improved oxidation performance of MoSi₂ (Cabouro et al., 2007, Cabouro et al., 2008, Knittel et al., 2010), Bernard et al., 2010. In the course of our studies focused on the evaluation of the effect of elemental substitutions, we studied the isothermal section of the ternary phase diagram Mo—Pt—Si at 1423 K. Two new phases of composition MoPt₂Si₃ and MoPt₃Si₄ were identified (Littner, 2003), and MoPt₃Si₄ was indexed in the orthorhombic system: a = 5.5096 Å, b = 3.493 Å, c = 24.294 Å. The structure of MoPt₃Si₄ was recently published by Joubert et al. (2010), from powder X-ray diffraction data. It turned out that the MoPt₃Si₄ structure can be derived from PtSi by an ordered substitution of Pt by Mo. The atomic arrangement along the c axis leads to a fourfold superstructure, with c(MoPt₃Si₄) = 4 × c(PtSi). Our analysis based on single-crystal data confirms the previous results but yields more accurate atomic positions, approximately by one order of magnitude. Additionally, this also allows determination of anisotropic displacement parameters (Fig. 1). Fig. 2 shows the coordination polyhedra. The coordination number for each d metal is 10, for Si it is 8. Mo and Pt exhibit different coordination polyhedra. In both cases, these are based on bicapped-square antiprisms, but with two additional vertices in cis-positions for Mo whereas they are in trans-positions for Pt (as in PtSi). The coordination polyhedra for Si1, Si2 and Si3 atoms can be considered as highly deformed square antiprisms (as in PtSi), while Si4 has a bicapped trigonal prismatic coordination geometry. Shortest and longest interatomic distances for each coordination polyedra are reported in Table 1. The shortest distances found for Mo—Si and Pt—Si are 2.535 (2) Å and of 2.387 (3) Å respectively. These may be compared to the values given by Joubert et al. (2010), namely 2.463 Å and 2.355 Å.

Figure 3 also emphasizes that the corrugated ribbons formed by the silicon sub-network and expanded along the c axis are greatly distorted compared to the PtSi parent structure.

Related literature top

For general background to molybden silicides, see: Littner (2003); Benarchid et al. (2009); Bernard et al. (2010); Cabouro et al. (2007, 2008); Fitzer (1955); Knittel et al. (2010). For the structure determination of the title compound from standard powder diffraction data, see: Joubert et al. (2010).

For the PAP correction program, see: Pouchou & Pichoir (1984).

Experimental top

Metal powders with nominal purities > 99.9 (Pt sponge 270 mesh - Engelhard - Clal, Si and Mo 325 mesh: Cerac) were mixed in different atomic ratios corresponding to alloys belonging to the MoSi₂—Mo₅Si₃—PtSi domain. An ingot was prepared by high frequency melting, and stabilized in a thermodynamic equilibrium for 100 h at 1150°C under argon. Single crystals of Pt₃MoSi₄ were directly isolated from the crushed ingot. A part of the ingot was embedded in an epoxy resin, polished and microanalyzed by an electron probe (SX 50 CAMECA, - PAP correction program (Pouchou & Pichoir, 1984). The EPMA composition corresponds, within the accuracy of the measurement, to that obtained by the structural determination.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Plot of the asymmetric unit of MoPt₃Si₄. The displacement ellipsoids are drawn at the 75% probability level. Atoms are bonded for interatomic distances lower than 3.1 Å.
	Fig. 2. The unit cell and the coordination polyhedra of the atoms in the structure of MoPt₃Si₄. Si in blue, Pt in light grey, Mo in yellow.
	Fig. 3. Corrugated ribbons from Si atoms in the structure of PtSi and MoPt₃Si₄.

Molybdenum triplatinum tetrasilicide top

Crystal data top

MoPt₃Si₄	D_x = 11.256 Mg m⁻³
M_r = 793.57	Melting point: 1503 K
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 4246 reflections
a = 5.5121 (2) Å	θ = 3.4–33.7°
b = 3.4951 (1) Å	µ = 92.80 mm⁻¹
c = 24.3078 (7) Å	T = 297 K
V = 468.30 (3) Å³	Needle, metallic colourless
Z = 4	0.12 × 0.03 × 0.03 mm
F(000) = 1328

Data collection top

Bruker APEXII QUAZAR CCD diffractometer	1060 independent reflections
Radiation source: ImuS	955 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.040
ω scans	θ_max = 33.7°, θ_min = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −8→8
T_min = 0.031, T_max = 0.174	k = −5→5
9779 measured reflections	l = −34→37

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.029	w = 1/[σ²(F_o²) + (0.0069P)² + 14.4673P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.067	(Δ/σ)_max = 0.001
S = 1.41	Δρ_max = 2.16 e Å⁻³
1060 reflections	Δρ_min = −3.81 e Å⁻³
50 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00129 (7)

Crystal data top

MoPt₃Si₄	V = 468.30 (3) Å³
M_r = 793.57	Z = 4
Orthorhombic, Pnma	Mo Kα radiation
a = 5.5121 (2) Å	µ = 92.80 mm⁻¹
b = 3.4951 (1) Å	T = 297 K
c = 24.3078 (7) Å	0.12 × 0.03 × 0.03 mm

Data collection top

Bruker APEXII QUAZAR CCD diffractometer	1060 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2004)	955 reflections with I > 2σ(I)
T_min = 0.031, T_max = 0.174	R_int = 0.040
9779 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.067	w = 1/[σ²(F_o²) + (0.0069P)² + 14.4673P] where P = (F_o² + 2F_c²)/3
S = 1.41	Δρ_max = 2.16 e Å⁻³
1060 reflections	Δρ_min = −3.81 e Å⁻³
50 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Pt1	0.50285 (7)	0.2500	0.547907 (16)	0.00783 (11)
Pt2	0.00468 (7)	−0.2500	0.669289 (16)	0.00688 (11)
Pt3	0.00210 (7)	0.2500	0.574730 (17)	0.00783 (11)
Mo1	−0.49497 (15)	−0.2500	0.71035 (4)	0.00562 (16)
Si1	0.6616 (6)	−0.2500	0.60935 (12)	0.0071 (5)
Si2	0.3216 (6)	0.2500	0.64573 (12)	0.0072 (5)
Si3	0.1790 (6)	−0.2500	0.51984 (12)	0.0076 (5)
Si4	−0.1678 (6)	−0.7500	0.72502 (12)	0.0071 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.00828 (19)	0.00729 (18)	0.00793 (19)	0.000	0.00011 (13)	0.000
Pt2	0.00732 (18)	0.00574 (16)	0.00759 (19)	0.000	0.00034 (13)	0.000
Pt3	0.00835 (18)	0.00728 (17)	0.00787 (18)	0.000	−0.00006 (13)	0.000
Mo1	0.0068 (3)	0.0044 (3)	0.0057 (3)	0.000	0.0003 (3)	0.000
Si1	0.0086 (11)	0.0063 (11)	0.0064 (12)	0.000	−0.0006 (10)	0.000
Si2	0.0092 (12)	0.0055 (12)	0.0068 (12)	0.000	−0.0021 (10)	0.000
Si3	0.0090 (12)	0.0063 (12)	0.0075 (11)	0.000	0.0004 (10)	0.000
Si4	0.0099 (12)	0.0033 (11)	0.0082 (12)	0.000	−0.0006 (10)	0.000

Geometric parameters (Å, º) top

Pt1—Si3ⁱ	2.406 (3)	Mo1—Si1^v	2.602 (3)
Pt1—Si1	2.460 (2)	Mo1—Pt2^xi	2.9256 (10)
Pt1—Si1ⁱⁱ	2.460 (2)	Mo1—Pt2	2.929 (1)
Pt1—Si2	2.579 (3)	Mo1—Pt2^v	2.9331 (10)
Pt1—Si3	2.590 (2)	Si1—Pt2ⁱⁱⁱ	2.387 (3)
Pt1—Si3ⁱⁱ	2.590 (2)	Si1—Pt1^vi	2.460 (2)
Pt1—Pt3ⁱⁱⁱ	2.8281 (6)	Si1—Pt1	2.460 (2)
Pt1—Pt3	2.8362 (6)	Si1—Mo1ⁱⁱⁱ	2.602 (3)
Pt1—Pt1ⁱ	2.9119 (6)	Si1—Pt3ⁱⁱⁱ	2.699 (2)
Pt1—Pt1^iv	2.9119 (6)	Si1—Pt3^xiii	2.699 (2)
Pt2—Si1^v	2.387 (3)	Si1—Si2^vi	2.711 (3)
Pt2—Si4ⁱⁱ	2.407 (2)	Si1—Si2	2.711 (3)
Pt2—Si4	2.407 (2)	Si2—Pt3	2.466 (3)
Pt2—Si2	2.536 (2)	Si2—Pt2ⁱⁱ	2.536 (2)
Pt2—Si2^vi	2.536 (2)	Si2—Pt2	2.536 (2)
Pt2—Pt3^vi	2.8874 (5)	Si2—Mo1^xiv	2.558 (2)
Pt2—Pt3	2.8874 (5)	Si2—Mo1ⁱⁱⁱ	2.558 (2)
Pt2—Mo1^vii	2.9255 (10)	Si2—Pt1	2.579 (3)
Pt2—Mo1	2.9294 (10)	Si2—Si1ⁱⁱ	2.711 (3)
Pt2—Mo1ⁱⁱⁱ	2.9331 (10)	Si2—Si1	2.711 (3)
Pt3—Si3	2.405 (2)	Si3—Pt1^vi	2.590 (2)
Pt3—Si3ⁱⁱ	2.405 (2)	Si3—Pt1	2.590 (2)
Pt3—Si2	2.466 (3)	SI3—Pt3	2.405 (2)
Pt3—Si3^viii	2.506 (3)	Si3—Pt3^vi	2.405 (2)
Pt3—Si1^v	2.699 (2)	Si3—Pt1ⁱ	2.406 (3)
Pt3—Si1^ix	2.699 (2)	Si3—Pt3^viii	2.506 (3)
Pt3—Pt1^v	2.8281 (6)	Si3—Si3^xv	2.807 (5)
Pt3—Pt1	2.836 (1)	Si3—Si3^viii	2.807 (5)
Pt3—Pt2ⁱⁱ	2.8874 (5)	Si4—Pt2^vi	2.407 (2)
Pt3—Pt2	2.8874 (5)	Si4—Pt2	2.407 (2)
Mo1—Si4	2.535 (2)	Si4—Mo1^vii	2.535 (2)
Mo1—Si4ⁱⁱ	2.537 (2)	Si4—Mo1^xvi	2.535 (2)
Mo1—Si4^x	2.535 (2)	Si4—Mo1^vi	2.537 (2)
Mo1—Si4^xi	2.535 (2)	Si4—Mo1	2.536 (2)
Mo1—Si2^xii	2.558 (2)	Si4—Si4^vii	3.012 (5)
Mo1—Si2^v	2.558 (2)	Si4—Si4^xi	3.012 (5)

Si3ⁱ—Pt1—Si1	98.99 (9)	Si4ⁱⁱ—Mo1—Si4	87.10 (10)
Si3ⁱ—Pt1—Si1ⁱⁱ	98.99 (9)	Si4^x—Mo1—Si2^xii	134.65 (10)
Si1—Pt1—Si1ⁱⁱ	90.54 (10)	Si4^xi—Mo1—Si2^xii	76.18 (8)
Si3ⁱ—Pt1—Si2	155.99 (10)	Si4ⁱⁱ—Mo1—Si2^xii	146.93 (10)
Si1—Pt1—Si2	65.04 (8)	Si4—Mo1—Si2^xii	84.07 (8)
Si1ⁱⁱ—Pt1—Si2	65.04 (8)	Si4^x—Mo1—Si2^v	76.18 (8)
Si3ⁱ—Pt1—Si3	108.80 (8)	Si4^xi—Mo1—Si2^v	134.65 (10)
Si1—Pt1—Si3	85.75 (8)	Si4ⁱⁱ—Mo1—Si2^v	84.07 (8)
Si1ⁱⁱ—Pt1—Si3	152.21 (10)	Si4—Mo1—Si2^v	146.93 (10)
Si2—Pt1—Si3	88.61 (8)	Si2^xii—Mo1—Si2^v	86.18 (9)
Si3ⁱ—Pt1—Si3ⁱⁱ	108.80 (8)	Si4^x—Mo1—Si1^v	135.16 (5)
Si1—Pt1—Si3ⁱⁱ	152.21 (10)	Si4^xi—Mo1—Si1^v	135.16 (5)
Si1ⁱⁱ—Pt1—Si3ⁱⁱ	85.75 (8)	Si4ⁱⁱ—Mo1—Si1^v	84.07 (9)
Si2—Pt1—Si3ⁱⁱ	88.61 (8)	Si4—Mo1—Si1^v	84.08 (9)
Si3—Pt1—Si3ⁱⁱ	84.88 (9)	Si2^xii—Mo1—Si1^v	63.37 (8)
Si3ⁱ—Pt1—Pt3ⁱⁱⁱ	56.52 (7)	Si2^v—Mo1—Si1^v	63.37 (8)
Si1—Pt1—Pt3ⁱⁱⁱ	60.91 (7)	Si4^x—Mo1—Pt2^xi	51.70 (6)
Si1ⁱⁱ—Pt1—Pt3ⁱⁱⁱ	60.91 (7)	Si4^xi—Mo1—Pt2^xi	51.70 (6)
Si2—Pt1—Pt3ⁱⁱⁱ	99.47 (7)	Si4ⁱⁱ—Mo1—Pt2^xi	81.95 (7)
Si3—Pt1—Pt3ⁱⁱⁱ	137.02 (5)	Si4—Mo1—Pt2^xi	81.94 (7)
Si3ⁱⁱ—Pt1—Pt3ⁱⁱⁱ	137.02 (5)	Si2^xii—Mo1—Pt2^xi	127.87 (6)
Si3ⁱ—Pt1—Pt3	150.09 (8)	Si2^v—Mo1—Pt2^xi	127.87 (6)
Si1—Pt1—Pt3	101.93 (7)	Si1^v—Mo1—Pt2^xi	160.67 (8)
Si1ⁱⁱ—Pt1—Pt3	101.93 (7)	Si4^x—Mo1—Pt2	124.35 (7)
Si2—Pt1—Pt3	53.91 (7)	Si4^xi—Mo1—Pt2	124.35 (7)
Si3—Pt1—Pt3	52.39 (6)	Si4ⁱⁱ—Mo1—Pt2	51.64 (6)
Si3ⁱⁱ—Pt1—Pt3	52.39 (6)	Si4—Mo1—Pt2	51.64 (6)
Pt3ⁱⁱⁱ—Pt1—Pt3	153.38 (2)	Si2^xii—Mo1—Pt2	99.35 (7)
Si3ⁱ—Pt1—Pt1ⁱ	57.34 (5)	Si2^v—Mo1—Pt2	99.35 (7)
Si1—Pt1—Pt1ⁱ	93.62 (5)	Si1^v—Mo1—Pt2	50.71 (7)
Si1ⁱⁱ—Pt1—Pt1ⁱ	156.33 (7)	Pt2^xi—Mo1—Pt2	109.96 (3)
Si2—Pt1—Pt1ⁱ	137.15 (4)	Si4^x—Mo1—Pt2^v	81.81 (7)
Si3—Pt1—Pt1ⁱ	51.45 (7)	Si4^xi—Mo1—Pt2^v	81.81 (7)
Si3ⁱⁱ—Pt1—Pt1ⁱ	100.77 (6)	Si4ⁱⁱ—Mo1—Pt2^v	135.76 (5)
Pt3ⁱⁱⁱ—Pt1—Pt1ⁱ	101.239 (19)	Si4—Mo1—Pt2^v	135.76 (5)
Pt3—Pt1—Pt1ⁱ	99.983 (19)	Si2^xii—Mo1—Pt2^v	54.50 (6)
Si3ⁱ—Pt1—Pt1^iv	57.34 (5)	Si2^v—Mo1—Pt2^v	54.50 (6)
Si1—Pt1—Pt1^iv	156.33 (7)	Si1^v—Mo1—Pt2^v	89.47 (7)
Si1ⁱⁱ—Pt1—Pt1^iv	93.62 (5)	Pt2^xi—Mo1—Pt2^v	109.86 (3)
Si2—Pt1—Pt1^iv	137.15 (4)	Pt2—Mo1—Pt2^v	140.18 (4)
Si3—Pt1—Pt1^iv	100.77 (6)	Pt2ⁱⁱⁱ—Si1—Pt1	130.73 (7)
Si3ⁱⁱ—Pt1—Pt1^iv	51.45 (7)	Pt2ⁱⁱⁱ—Si1—Pt1^vi	130.73 (7)
Pt3ⁱⁱⁱ—Pt1—Pt1^iv	101.239 (19)	Pt1—Si1—Pt1^vi	90.54 (10)
Pt3—Pt1—Pt1^iv	99.983 (19)	Pt2ⁱⁱⁱ—Si1—Mo1ⁱⁱⁱ	71.76 (8)
Pt1ⁱ—Pt1—Pt1^iv	73.760 (19)	Pt1—Si1—Mo1ⁱⁱⁱ	117.05 (9)
Si1^v—Pt2—Si4ⁱⁱ	91.76 (9)	Pt1^vi—Si1—Mo1ⁱⁱⁱ	117.05 (9)
Si1^v—Pt2—Si4	91.76 (9)	Pt2ⁱⁱⁱ—Si1—Pt3ⁱⁱⁱ	68.87 (7)
Si4ⁱⁱ—Pt2—Si4	93.12 (11)	Pt1—Si1—Pt3ⁱⁱⁱ	66.30 (4)
Si1^v—Pt2—Si2	114.06 (8)	Pt1^vi—Si1—Pt3ⁱⁱⁱ	121.20 (11)
Si4ⁱⁱ—Pt2—Si2	84.19 (8)	Mo1ⁱⁱⁱ—Si1—Pt3ⁱⁱⁱ	121.65 (8)
Si4—Pt2—Si2	154.07 (10)	Pt2ⁱⁱⁱ—Si1—Pt3^xiii	68.87 (7)
Si1^v—Pt2—Si2^vi	114.06 (8)	Pt1—Si1—Pt3^xiii	121.20 (11)
Si4ⁱⁱ—Pt2—Si2^vi	154.07 (10)	Pt1^vi—Si1—Pt3^xiii	66.30 (4)
Si4—Pt2—Si2^vi	84.19 (8)	Mo1ⁱⁱⁱ—Si1—Pt3^xiii	121.65 (8)
Si2—Pt2—Si2^vi	87.10 (10)	Pt3ⁱⁱⁱ—Si1—Pt3^xiii	80.71 (9)
Si1^v—Pt2—Pt3^vi	60.68 (5)	Pt2ⁱⁱⁱ—Si1—Si2	110.40 (11)
Si4ⁱⁱ—Pt2—Pt3^vi	152.32 (7)	Pt1—Si1—Si2	59.61 (7)
Si4—Pt2—Pt3^vi	90.38 (6)	Pt1^vi—Si1—Si2	114.21 (13)
Si2—Pt2—Pt3^vi	103.92 (6)	Mo1ⁱⁱⁱ—Si1—Si2	57.52 (8)
Si2^vi—Pt2—Pt3^vi	53.60 (6)	Pt3ⁱⁱⁱ—Si1—Si2	99.50 (4)
Si1^v—Pt2—Pt3	60.68 (5)	Pt3^xiii—Si1—Si2	179.13 (14)
Si4ⁱⁱ—Pt2—Pt3	90.38 (6)	Pt2ⁱⁱⁱ—Si1—Si2^vi	110.40 (11)
Si4—Pt2—Pt3	152.32 (7)	Pt1—Si1—Si2^vi	114.21 (13)
Si2—Pt2—Pt3	53.60 (6)	Pt1^vi—Si1—Si2^vi	59.61 (7)
Si2^vi—Pt2—Pt3	103.93 (6)	Mo1ⁱⁱⁱ—Si1—Si2^vi	57.52 (8)
Pt3^vi—Pt2—Pt3	74.490 (14)	Pt3ⁱⁱⁱ—Si1—Si2^vi	179.13 (14)
Si1^v—Pt2—Mo1^vii	127.65 (7)	Pt3^xiii—Si1—Si2^vi	99.50 (4)
Si4ⁱⁱ—Pt2—Mo1^vii	55.76 (6)	Si2—Si1—Si2^vi	80.27 (12)
Si4—Pt2—Mo1^vii	55.76 (6)	Pt3—Si2—Pt2ⁱⁱ	70.50 (7)
Si2—Pt2—Mo1^vii	103.02 (7)	Pt3—Si2—Pt2	70.50 (7)
Si2^vi—Pt2—Mo1^vii	103.02 (7)	Pt2ⁱⁱ—Si2—Pt2	87.10 (10)
Pt3^vi—Pt2—Mo1^vii	142.754 (7)	Pt3—Si2—Mo1^xiv	135.41 (6)
Pt3—Pt2—Mo1^vii	142.754 (7)	Pt2ⁱⁱ—Si2—Mo1^xiv	70.30 (5)
Si1^v—Pt2—Mo1	57.54 (7)	Pt2—Si2—Mo1^xiv	127.17 (12)
Si4ⁱⁱ—Pt2—Mo1	55.73 (7)	Pt3—Si2—Mo1ⁱⁱⁱ	135.41 (6)
Si4—Pt2—Mo1	55.73 (7)	Pt2ⁱⁱ—Si2—Mo1ⁱⁱⁱ	127.17 (12)
Si2—Pt2—Mo1	136.42 (5)	Pt2—Si2—Mo1ⁱⁱⁱ	70.30 (5)
Si2^vi—Pt2—Mo1	136.42 (5)	Mo1^xiv—Si2—Mo1ⁱⁱⁱ	86.17 (9)
Pt3^vi—Pt2—Mo1	105.463 (19)	Pt3—Si2—Pt1	68.37 (8)
Pt3—Pt2—Mo1	105.463 (19)	Pt2ⁱⁱ—Si2—Pt1	118.36 (8)
Mo1^vii—Pt2—Mo1	70.12 (2)	Pt2—Si2—Pt1	118.36 (8)
Si1^v—Pt2—Mo1ⁱⁱⁱ	162.29 (8)	Mo1^xiv—Si2—Pt1	114.39 (9)
Si4ⁱⁱ—Pt2—Mo1ⁱⁱⁱ	100.36 (8)	Mo1ⁱⁱⁱ—Si2—Pt1	114.39 (9)
Si4—Pt2—Mo1ⁱⁱⁱ	100.36 (8)	Pt3—Si2—Si1ⁱⁱ	105.40 (11)
Si2—Pt2—Mo1ⁱⁱⁱ	55.20 (6)	Pt2ⁱⁱ—Si2—Si1ⁱⁱ	96.07 (4)
Si2^vi—Pt2—Mo1ⁱⁱⁱ	55.20 (6)	Pt2—Si2—Si1ⁱⁱ	173.71 (13)
Pt3^vi—Pt2—Mo1ⁱⁱⁱ	105.996 (19)	Mo1^xiv—Si2—Si1ⁱⁱ	59.11 (7)
Pt3—Pt2—Mo1ⁱⁱⁱ	105.996 (19)	Mo1ⁱⁱⁱ—Si2—Si1ⁱⁱ	111.55 (13)
Mo1^vii—Pt2—Mo1ⁱⁱⁱ	70.06 (2)	Pt1—Si2—Si1ⁱⁱ	55.35 (8)
Mo1—Pt2—Mo1ⁱⁱⁱ	140.18 (4)	Pt3—Si2—Si1	105.40 (11)
Si3—Pt3—Si3ⁱⁱ	93.20 (11)	Pt2ⁱⁱ—Si2—Si1	173.71 (13)
Si3—Pt3—Si2	95.67 (9)	Pt2—Si2—Si1	96.07 (4)
Si3ⁱⁱ—Pt3—Si2	95.67 (9)	Mo1^xiv—Si2—Si1	111.55 (13)
Si3—Pt3—Si3^viii	69.67 (9)	Mo1ⁱⁱⁱ—Si2—Si1	59.11 (7)
Si3ⁱⁱ—Pt3—Si3^viii	69.67 (9)	Pt1—Si2—Si1	55.35 (8)
Si2—Pt3—Si3^viii	157.89 (10)	Si1ⁱⁱ—Si2—Si1	80.27 (12)
Si3—Pt3—Si1^v	89.11 (7)	Pt3—Si3—Pt3^vi	93.20 (11)
Si3ⁱⁱ—Pt3—Si1^v	157.71 (9)	Pt3—Si3—Pt1ⁱ	132.47 (6)
Si2—Pt3—Si1^v	106.16 (8)	Pt3^vi—Si3—Pt1ⁱ	132.47 (6)
Si3^viii—Pt3—Si1^v	90.52 (8)	Pt3—Si3—Pt3^viii	110.33 (9)
Si3—Pt3—Si1^ix	157.72 (9)	Pt3^vi—Si3—Pt3^viii	110.33 (9)
Si3ⁱⁱ—Pt3—Si1^ix	89.11 (7)	Pt1ⁱ—Si3—Pt3^viii	70.27 (8)
Si2—Pt3—Si1^ix	106.16 (8)	Pt3—Si3—Pt1^vi	128.58 (13)
Si3^viii—Pt3—Si1^ix	90.52 (8)	Pt3^vi—Si3—Pt1^vi	69.08 (4)
Si1^v—Pt3—Si1^ix	80.71 (9)	Pt1ⁱ—Si3—Pt1^vi	71.20 (7)
Si3—Pt3—Pt1^v	105.46 (7)	Pt3^viii—Si3—Pt1^vi	121.08 (9)
Si3ⁱⁱ—Pt3—Pt1^v	105.46 (7)	Pt3—Si3—Pt1	69.08 (4)
Si2—Pt3—Pt1^v	148.91 (8)	Pt3^vi—Si3—Pt1	128.58 (13)
Si3^viii—Pt3—Pt1^v	53.20 (7)	Pt1ⁱ—Si3—Pt1	71.20 (7)
Si1^v—Pt3—Pt1^v	52.79 (6)	Pt3^viii—Si3—Pt1	121.08 (9)
Si1^ix—Pt3—Pt1^v	52.79 (6)	Pt1^vi—Si3—Pt1	84.88 (9)
Si3—Pt3—Pt1	58.53 (7)	Pt3—Si3—Si3^xv	110.98 (16)
Si3ⁱⁱ—Pt3—Pt1	58.53 (7)	Pt3^vi—Si3—Si3^xv	56.86 (7)
Si2—Pt3—Pt1	57.71 (7)	Pt1ⁱ—Si3—Si3^xv	106.10 (14)
Si3^viii—Pt3—Pt1	100.18 (7)	Pt3^viii—Si3—Si3^xv	53.47 (10)
Si1^v—Pt3—Pt1	138.45 (5)	Pt1^vi—Si3—Si3^xv	98.92 (3)
Si1^ix—Pt3—Pt1	138.45 (5)	Pt1—Si3—Si3^xv	174.46 (16)
Pt1^v—Pt3—Pt1	153.38 (2)	Pt3—Si3—Si3^viii	56.86 (7)
Si3—Pt3—Pt2ⁱⁱ	151.56 (8)	Pt3^vi—Si3—Si3^viii	110.98 (16)
Si3ⁱⁱ—Pt3—Pt2ⁱⁱ	89.99 (6)	Pt1ⁱ—Si3—Si3^viii	106.10 (14)
Si2—Pt3—Pt2ⁱⁱ	55.90 (5)	Pt3^viii—Si3—Si3^viii	53.47 (10)
Si3^viii—Pt3—Pt2ⁱⁱ	137.07 (3)	Pt1^vi—Si3—Si3^viii	174.46 (16)
Si1^v—Pt3—Pt2ⁱⁱ	98.46 (5)	Pt1—Si3—Si3^viii	98.92 (3)
Si1^ix—Pt3—Pt2ⁱⁱ	50.46 (6)	Si3^xv—Si3—Si3^viii	77.02 (16)
Pt1^v—Pt3—Pt2ⁱⁱ	100.856 (15)	Pt2—Si4—Pt2^vi	93.11 (11)
Pt1—Pt3—Pt2ⁱⁱ	100.265 (15)	Pt2—Si4—Mo1^vii	72.54 (5)
Si3—Pt3—Pt2	89.99 (6)	Pt2^vi—Si4—Mo1^vii	134.49 (14)
Si3ⁱⁱ—Pt3—Pt2	151.57 (8)	Pt2—Si4—Mo1^xvi	134.49 (14)
Si2—Pt3—Pt2	55.90 (5)	Pt2^vi—Si4—Mo1^xvi	72.54 (5)
Si3^viii—Pt3—Pt2	137.07 (3)	Mo1^vii—Si4—Mo1^xvi	87.14 (10)
Si1^v—Pt3—Pt2	50.46 (6)	Pt2—Si4—Mo1^vi	134.58 (13)
Si1^ix—Pt3—Pt2	98.46 (5)	Pt2^vi—Si4—Mo1^vi	72.63 (4)
Pt1^v—Pt3—Pt2	100.855 (15)	Mo1^vii—Si4—Mo1^vi	146.00 (13)
Pt1—Pt3—Pt2	100.265 (15)	Mo1^xvi—Si4—Mo1^vi	83.07 (4)
Pt2ⁱⁱ—Pt3—Pt2	74.490 (14)	Pt2—Si4—Mo1	72.63 (4)
Si4^x—Mo1—Si4^xi	87.14 (10)	Pt2^vi—Si4—Mo1	134.58 (13)
Si4^x—Mo1—Si4ⁱⁱ	72.85 (5)	Mo1^vii—Si4—Mo1	83.07 (4)
Si4^xi—Mo1—Si4ⁱⁱ	130.91 (7)	Mo1^xvi—Si4—Mo1	146.01 (13)
Si4^x—Mo1—Si4	130.91 (6)	Mo1^vi—Si4—Mo1	87.10 (10)
Si4^xi—Mo1—Si4	72.85 (5)

Symmetry codes: (i) −x+1, −y, −z+1; (ii) x, y+1, z; (iii) x+1, y, z; (iv) −x+1, −y+1, −z+1; (v) x−1, y, z; (vi) x, y−1, z; (vii) x+1/2, y, −z+3/2; (viii) −x, −y, −z+1; (ix) x−1, y+1, z; (x) x−1/2, y+1, −z+3/2; (xi) x−1/2, y, −z+3/2; (xii) x−1, y−1, z; (xiii) x+1, y−1, z; (xiv) x+1, y+1, z; (xv) −x, −y−1, −z+1; (xvi) x+1/2, y−1, −z+3/2.

Experimental details

Crystal data
Chemical formula	MoPt₃Si₄
M_r	793.57
Crystal system, space group	Orthorhombic, Pnma
Temperature (K)	297
a, b, c (Å)	5.5121 (2), 3.4951 (1), 24.3078 (7)
V (Å³)	468.30 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	92.80
Crystal size (mm)	0.12 × 0.03 × 0.03

Data collection
Diffractometer	Bruker APEXII QUAZAR CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2004)
T_min, T_max	0.031, 0.174
No. of measured, independent and observed [I > 2σ(I)] reflections	9779, 1060, 955
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.781

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.067, 1.41
No. of reflections	1060
No. of parameters	50
	w = 1/[σ²(F_o²) + (0.0069P)² + 14.4673P] where P = (F_o² + 2F_c²)/3
Δρ_max, Δρ_min (e Å⁻³)	2.16, −3.81

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999) and ORTEP-3 (Farrugia, 1997).

Selected bond lengths (Å) top

Pt1—Si3ⁱ	2.406 (3)	Si1—Pt2^iv	2.387 (3)
Pt1—Pt1ⁱⁱ	2.9119 (6)	Si1—Si2	2.711 (3)
Pt2—Si1ⁱⁱⁱ	2.387 (3)	Si2—Pt3	2.466 (3)
Pt2—Mo1^iv	2.9331 (10)	Si2—Si1	2.711 (3)
Pt3—Si3	2.405 (2)	Si3—Pt1^v	2.590 (2)
Pt3—Pt2	2.8874 (5)	Si3—Si3^vi	2.807 (5)
Mo1—Si4	2.535 (2)	Si4—Pt2^v	2.407 (2)
Mo1—Pt2ⁱⁱⁱ	2.9331 (10)	Si4—Si4^vii	3.012 (5)

Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+1, −y+1, −z+1; (iii) x−1, y, z; (iv) x+1, y, z; (v) x, y−1, z; (vi) −x, −y, −z+1; (vii) x−1/2, y, −z+3/2.

Acknowledgements

We thank Dr Holger Ott (Bruker AXS GmbH, Karlsruhe, Germany) for the data collection and the 'Service Commun de Microanalyse' (Faculté des Sciences et Techniques, Vandoeuvre les Nancy, France).

References

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